1. Field of the Invention
The present invention relates generally to piezoelectric components and, more particularly, to a piezoelectric component such as an oscillator, a discriminator or a filter having a piezoelectric resonator adapted to generate longitudinal vibration.
2. Description of the Related Art
FIG. 13 is a perspective view of a conventional piezoelectric component 1. The piezoelectric component 1 includes a supporting substrate 2 having pattern electrodes 3a and 3b disposed on a surface of the substrate 2. A piezoelectric resonator 4 is supported on the supporting substrate 2. The piezoelectric resonator 4 includes, for example, a vibrating body 5 formed of a piezoelectric material and external electrodes 6a and 6b disposed on two opposite surfaces of the vibrating body 5. When a signal is input between the external electrodes 6a and 6b, vibration in a longitudinal mode is generated in the vibrating body 5. A supporting member 7 is formed of, for example, an electroconductive material on the pattern electrode 3a. A central portion of the piezoelectric resonator 4 is supported by the supporting member 7. Simultaneously, the external electrode 6a of the piezoelectric resonator 4 and the pattern electrode 3a are electrically connected to each other by the supporting member 7. The other external electrode 6b of the piezoelectric resonator 4 is connected to the pattern electrode 3b by a lead wire 8.
In the piezoelectric component 1 having the structure described above, in order to obtain desired electrical characteristics, a plurality of factors including a resonant frequency, a degree of polarization and a capacitance between the terminals 6a, 6b of the piezoelectric resonator 4, and others, are determined according to component size requirements for the piezoelectric resonator 4 and intended working conditions.
The piezoelectric resonator has a specific mechanical quality factor Qm according to the piezoelectric material used. As a result, in order to obtain a desired value of Qm for a piezoelectric resonator, it has been necessary to develop an optimal piezoelectric material for achieving the desired value or a piezoelectric material capable of achieving a value close to the desired value of the electrical characteristics. A long period of time is usually required to develop such a specific optimal piezoelectric material. If a piezoelectric material capable of achieving a value of electrical characteristic which is not equal to but close to the desired value is used, it is necessary to tolerate a range of values of electrical characteristics which do not correspond to the desired electrical characteristics.